The present invention relates to a control device for a lockable gas spring.
Lockable gas springs are used in numerous devices (beds, armchairs, stands etc.) to ensure infinitely variable adjustment, balancing of a weight, and speed control; these three functions are executed together or separately. The springs are equipped with a control finger located at one of their ends (rod side or tube side). This finger must be axially displaced by a few millimeters and returns automatically; the displacement is always towards the gas spring piston. The gas spring is usually mounted between a fixed point and a pivoting movable point which makes the execution of this control problematic. The reason for this is that when the gas spring is operated it pivots about its fixed point as a result of the movable point describing an arc of a circle and therefore a control device adapted to this pivoting movement must be provided.
It has been proposed, in FR-A-2,461,851, to use a U-shaped resilient leaf, one arm of which is integral with the gas spring and the other arm of which bears against the head of the control finger. A cable assembly is provided for the displacement of this arm of the leaf. This system is complex and very expensive.
In some systems, cf. DE-U-1,955,308, an actuating lever is articulated about a fulcrum perpendicular to the axis of the gas spring and at a distance from this axis. When the lever pivots, its end causes the displacement of the head of the control finger. Because of the presence of a fulcrum and of a support, which is connected to the gas spring, for this fulcrum, this system has the disadvantage of being relatively expensive.
A device has been proposed, in DE-U-6,910,925, in which the finger of a locking device is actuated by a lever whose articulation consists merely of a hole which passes through a tubular element surrounding the finger. Additional components, however, are still necessary to prevent an undesirable displacement of the lever.
A mechanism has also been proposed, in EP-A-0,050,465, in which the actuating lever is held in two diametrically opposed orifices of a tubular component surrounding the actuating finger and bearing on the edge of either of these orifices in order to depress the finger. Grooves provided in the lever cooperate with the edges of the orifices or with the finger to prevent the lever from being dislodged, but a more considerable stress exerted upon the lever and directed simultaneously axially and radially may cause the lever to be dislodged from the location provided. This risk can be reduced by using an additional retaining spring, but assembly is then made more difficult.
The object of the present invention is to provide an actuating device in which the number of components is as small as possible and which nevertheless functions with a high degree of safety.